全文获取类型
收费全文 | 470篇 |
免费 | 24篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 156篇 |
金属工艺 | 2篇 |
机械仪表 | 3篇 |
建筑科学 | 22篇 |
能源动力 | 25篇 |
轻工业 | 34篇 |
水利工程 | 3篇 |
无线电 | 27篇 |
一般工业技术 | 79篇 |
冶金工业 | 56篇 |
原子能技术 | 10篇 |
自动化技术 | 73篇 |
出版年
2023年 | 8篇 |
2022年 | 29篇 |
2021年 | 40篇 |
2020年 | 11篇 |
2019年 | 8篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 14篇 |
2015年 | 16篇 |
2014年 | 13篇 |
2013年 | 37篇 |
2012年 | 30篇 |
2011年 | 32篇 |
2010年 | 20篇 |
2009年 | 23篇 |
2008年 | 21篇 |
2007年 | 27篇 |
2006年 | 14篇 |
2005年 | 16篇 |
2004年 | 23篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有494条查询结果,搜索用时 15 毫秒
31.
32.
Accidents caused by domino effect are among the more severe that took place in the chemical and process industry. However, a well established and widely accepted methodology for the quantitative assessment of domino accidents contribution to industrial risk is still missing. Hence, available data on damage to process equipment caused by blast waves were revised in the framework of quantitative risk analysis, aiming at the quantitative assessment of domino effects caused by overpressure. Specific probit models were derived for several categories of process equipment and were compared to other literature approaches for the prediction of probability of damage of equipment loaded by overpressure. The results evidence the importance of using equipment-specific models for the probability of damage and equipment-specific damage threshold values, rather than general equipment correlation, which may lead to errors up to 500%. 相似文献
33.
34.
Poly(ethylene terephthalate) (PET) is one of the most commonly employed polymers in the textile industry. Its relevance as a source of evidence in the reconstruction of criminal cases is nevertheless very limited because the properties and morphologies of fibers from different producers tend to be very similar. By integrating bands, obtained on single fibers by infrared (IR) microscopy, associated with trans and gauche conformation and to the O-H end-groups of the molecules, a method is proposed that can discriminate otherwise similar PET fibers. The absorbancies at 1370 and at 846 cm(-1) relative, respectively, to the gauche and trans conformation, were measured and ratioed. The end-group content was evaluated by ratioing the absorbancies of the signals at 3440 and at 874 cm(-1). Relative standard deviation (R. S. D.) was 1% for repetitive analyses on the same location of the same single fiber. Precision was reduced if the ratios were measured along the length of a single fiber (R. S. D. = 3%) and even further when different fibers of the same sample were examined (R. S. D. varied from 2 to 10%). This simple method can greatly enhance the evidential value of PET fibers by subclassifying them, thus helping the Court to better assess their significance. 相似文献
35.
Simoncelli and co-workers have proposed statistically-derived nonlinear divisive normalization models of the primary visual cortex (V1) that are consistent with the hypothesis that sensory systems are adapted to the signals to which they are exposed. In this paper, we present a more rigorous mathematical formulation and analysis of these statistically-derived models in terms of mutual information as a metric for statistical independence. We prove that the ad hoc choice of divisive normalization parameters proposed by Simoncelli and co-workers does not guarantee statistical independence between the output responses, but interestingly such choice does guarantee that each output response is statistically independent of almost all the linear inputs. This holds for the two different models of natural image statistics analysed theoretically, and is consistent with empirical results obtained on a set of natural images. 相似文献
36.
We compared the ability of auditory, visual, and audiovisual (bimodal) exogenous cues to capture visuo-spatial attention under conditions of no load versus high perceptual load. Participants had to discriminate the elevation (up vs. down) of visual targets preceded by either unimodal or bimodal cues under conditions of high perceptual load (in which they had to monitor a rapidly presented central stream of visual letters for occasionally presented target digits) or no perceptual load (in which the central stream was replaced by a fixation point). The results of 3 experiments showed that all 3 cues captured visuo-spatial attention in the no-load condition. By contrast, only the bimodal cues captured visuo-spatial attention in the high-load condition, indicating for the first time that multisensory integration can play a key role in disengaging spatial attention from a concurrent perceptually demanding stimulus. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
Tatiana S. de Araujo Zélia S. Macedo Petrus A. S. C. de Oliveira Mário E. G. Valerio 《Journal of Materials Science》2007,42(7):2236-2243
Pure and Cr3+-doped hydroxyapatite (HAP) were prepared via chemical precipitation route. The XRD measurements revealed that the typical
HAP powder pattern was obtained. SEM analysis indicated that aggregates of nanoparticles were formed. EDX analysis indicates
that the [Ca]/[P] concentration ratio was higher than the expected values but can be explained by the presence of carbonate
groups as dopants. The optical absorption spectra of the doped samples presented absorption bands typical of Cr3+ occupying to different crystalline sites. From the position of the bands, it was possible to estimate the crystal field parameters
for both sites of Cr3+ in the HAP matrix. The emission spectra of the Cr-doped samples were also investigated and typical transitions of the dopant
ion, in trivalent state, were identified. The potential use of the Cr3+-HAP as fluorescent probes for medical applications was discussed. 相似文献
38.
39.
Flexible aliphatic poly(isocyanurate–oxazolidone) resins based on poly(ethylene glycol) diglycidyl ether and 4,4′‐methylene dicyclohexyl diisocyanate 下载免费PDF全文
Ahmed Bakry Renato Aversano Lucio D'Ilario Valerio Di Lisio Iolanda Francolini Antonella Piozzi Andrea Martinelli 《应用聚合物科学杂志》2016,133(19)
New flexible aliphatic oxazolidone‐isocyanurate networks (AISOX) are obtained by reacting a low molecular weight diisocyanate (4,4′‐methylene dicyclohexyl diisocyanate, H12MDI) and a macro‐diepoxyde (poly(ethylene glycol) diglycidyl ether, Mn = 526, PEGDGE) in different molar ratio. The curing reaction, carried out from 25 °C to 200 °C, is studied by using DSC and FTIR. The effect of the molar ratio of the two monomers on thermal and mechanical properties of AISOX resins is investigated by DSC, thermogravimetric analysis, stress?strain measurements and optical microscopy. Independently from the feed composition, it is observed that the reaction steps are: (i) partial hydrolysis of isocyanate caused by water traces, (ii) incomplete trimerization of isocyanate to give isocyanurate, and (iii) formation of oxazolidone and complete conversion of isocyanate. At the highest concentration of the soft macrodiepoxyde (PEGDGE), the AISOX resin is in the rubbery state at room temperature and shows an elastomeric behavior. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43404. 相似文献
40.
Mnica Aguilera Valerio Rossini Ana Hickey Donjete Simnica Fiona Grady Valeria D. Felice Amy Moloney Lauren Pawley Aine Fanning Lorraine McCarthy Siobhan M. OMahony John F. Cryan Ken Nally Fergus Shanahan Silvia Melgar 《International journal of molecular sciences》2021,22(15)
Interactions between the intestinal microbiota, immune system and nervous system are essential for homeostasis in the gut. Inflammasomes contribute to innate immunity and brain–gut interactions, but their role in microbiota–neuro–immune interactions is not clear. Therefore, we investigated the effect of the inflammasome on visceral pain and local and systemic neuroimmune responses after antibiotic-induced changes to the microbiota. Wild-type (WT) and caspase-1/11 deficient (Casp1 KO) mice were orally treated for 2 weeks with an antibiotic cocktail (Abx, Bacitracin A and Neomycin), followed by quantification of representative fecal commensals (by qPCR), cecal short chain fatty acids (by HPLC), pathways implicated in the gut–neuro-immune axis (by RT-qPCR, immunofluorescence staining, and flow cytometry) in addition to capsaicin-induced visceral pain responses. Abx-treatment in WT-mice resulted in an increase in colonic macrophages, central neuro-immune interactions, colonic inflammasome and nociceptive receptor gene expression and a reduction in capsaicin-induced visceral pain. In contrast, these responses were attenuated in Abx-treated Casp1 KO mice. Collectively, the data indicate an important role for the inflammasome pathway in functional and inflammatory gastrointestinal conditions where pain and alterations in microbiota composition are prominent. 相似文献